Certain embodiments of the present invention generally relate to a connector for electronic equipment, and more particularly to a connector including an interchangeable tuner for controlling the impedance within the connector.
Connectors are known for interconnecting various electrical media, components, and structures such as printed circuit boards (PCB), coaxial cables, discrete circuit components, flex circuits and the like. The connectors may interconnect signal and/or power lines between two similar or different media, components and structures, such as between a flex circuit and a PCB, between two PCBs and the like. An example of an interconnection between two PCBs is a board-to-board connector. Connectors are offered in a variety of shapes and sizes, depending upon several competing criteria. Within connectors, the shape, size and spacing between contacts also greatly varies. As the shape, size and spacing of the contact changes, so does the impedance exhibited by the contacts.
Today, connectors are being proposed with more and more signal lines within smaller and smaller connector envelopes. Such size reductions and capacity increases have resulted in very close spacing between adjacent contacts within a connector. As contacts became more closely spaced, when carrying high speed signals, adjacent contacts begin to electrically couple with one another. Electrical coupling occurs when one contact becomes influenced by the electromagnetic field produced by an adjacent contact. Electrical coupling causes, among other things, the contacts to exhibit different impedance characteristics than they might otherwise exhibit absent any coupling. Until recently, impedance exhibited by a connector did not degrade performance by an appreciable amount, in part because signal/data transmission rates were relatively low (e.g., less than 500 MHz or 1 Gbits per second). However, newer electronic and electrical systems have been proposed that are able to transmit data signals at speeds approaching and exceeding 1 GHz or 2 Gbits per second. Because the speed of data transmission systems continues to increase, while the physical size of components continues to decrease, even small increases in impedance may pose significant problems, such as signal loss, within a connector and the system.
Many board-to-board systems have been proposed that include connectors that apply differential pairs of signals. Differential signal pairs include complimentary signals such that if one signal in a differential pair switches from 0 V to 1 V, the other signal in the differential pair switches from 1 V to 0 V. Differential pair connectors have been proposed that control impedance by using a predetermined contact-to-contact spacing (e.g., a distance between signal contacts of a differential pair). Impedance is affected by contact-to-contact spacing because impedance increases as capacitance decreases. Capacitance increases as the distance decreases between a signal contact, or tail, and ground or other signal contacts, or contacts. Hence, impedance decreases with decreased contact-to-contact spacing. Conversely, impedance increases with increased contact-to-contact spacing. Therefore, signal contacts of conventional systems are positioned a predetermined distance from adjacent signal contacts in order to yield a desired impedance.
As the distance increases between two contacts in a differential pair or otherwise, the contacts are considered to be xe2x80x9cloosely coupledxe2x80x9d to one another. Similarly, as the distance is decreased between contacts in a differential pair or otherwise, the contacts are considered to be more xe2x80x9ctightly coupledxe2x80x9d to one another. Loosening the coupling of signal contacts of a differential pair increases the impedance exhibited at the contacts, while tightening the coupling between signal contacts in a differential pair decreases the impedance.
Increasing the distance between signal contacts of a differential pair also increases the interference, noise and jitter experienced by the signals carried through circuit boards, the connector and contacts. For example, as a signal contact of a differential pair is displaced further from its complimentary signal contact, the signal contacts of one differential pair may become coupled to signal contacts of a different differential pair. As signal contacts of separate differential pairs become coupled to one another, the signal contacts begin to exhibit cross-talk with each other. That is, loosening the coupling between complimentary signal contacts may tighten the coupling between non-complimentary signal contacts. Tightening the coupling between non-complimentary signal contacts increases cross-talk between the contacts. Consequently, interference, noise, and jitter within the multi-layer circuit board, connector and system increases. Therefore, increasing the distance between signal contacts to increase the impedance within a particular differential pair causes a higher degree of interference, noise and jitter. Conversely, decreasing the distance between signal contacts of a differential pair to decrease the amount of interference, noise and jitter may produce a non-uniform or otherwise non-suitable impedance.
A need remains for an improved electrical connector capable of controlling impedance within desired levels.
In accordance with an embodiment of the present invention, a connector assembly has been developed that includes a connector housing having a contact retaining chamber at one end of the connector housing, at least two signal contacts arranged as a differential pair and held in the contact retaining chamber of the connector housing. The signal contacts are separated by a gap. The assembly also includes an impedance tuner block formed of a dielectric material insertable into the contact retaining chamber. The impedance tuner block has at least two channels notched therein. The impedance tuner block includes isolation layers separating the channels. Each channel receives a corresponding one of the signal contacts and each isolation layer is inserted between adjacent signal contacts when the impedance tuner block is inserted into the contact retaining chamber.
The impedance tuner block may also include a plurality of isolation ribs as the isolation layers. One isolation rib is positioned between two adjacent contacts. Optionally, the connector assembly may further include ground contacts separating the differential pairs from one another. The differential pairs may be separates from the ground contacts by the isolation ribs.
The connector assembly further includes at least one impedance adjusting insert securable to the impedance tuner block in a position that is oriented parallel to at least central elongate arms of the signal contacts. The impedance adjusting inserts may be formed of a non-ferrous metal.
Further, embodiments of the present invention include a shell covering the housing and the impedance tuner. The shell opens to allow removal of the impedance tuner. Upon removal of one impedance tuner, a different impedance tuner, having different impedance controlling characteristics may be positioned within the cavity of the electrical connector.